U.S. patent application number 12/473807 was filed with the patent office on 2009-12-03 for adhesive tape and its use.
This patent application is currently assigned to TESA SE. Invention is credited to Kerstin Gotz, Christoph NAGEL.
Application Number | 20090297833 12/473807 |
Document ID | / |
Family ID | 41026404 |
Filed Date | 2009-12-03 |
United States Patent
Application |
20090297833 |
Kind Code |
A1 |
NAGEL; Christoph ; et
al. |
December 3, 2009 |
ADHESIVE TAPE AND ITS USE
Abstract
An adhesive bonding system joins flat webs when changing rolls
of such webs. The adhesive bonding system comprises two adhesive
tape boundary edges, and further comprises a top carrier layer and
a bottom carrier layer, a flat connecting element that connects the
two carrier layers to one another and is suitable for opening the
connection under the conditions of a static or flying roll change.
At least one of the boundary edges of the connecting element does
not extend in a straight line, and a straight-line emphasis line is
defined in relation to this boundary edge, the emphasis line of
this boundary edge extends along a preferential direction, and this
boundary edge has a multiplicity of regions lying on one side of
its emphasis line and also a multiplicity of regions lying on the
other side of its emphasis line.
Inventors: |
NAGEL; Christoph; (Hamburg,
DE) ; Gotz; Kerstin; (Hamburg, DE) |
Correspondence
Address: |
NORRIS, MCLAUGHLIN & MARCUS, P.A.
875 THIRD AVE, 18TH FLOOR
NEW YORK
NY
10022
US
|
Assignee: |
TESA SE
HAMBURG
DE
|
Family ID: |
41026404 |
Appl. No.: |
12/473807 |
Filed: |
May 28, 2009 |
Current U.S.
Class: |
428/332 ;
156/157; 428/411.1; 428/702 |
Current CPC
Class: |
B65H 19/102 20130101;
C09J 2405/006 20130101; B65H 2301/41766 20130101; C09J 2203/342
20130101; Y10T 428/26 20150115; C09J 105/00 20130101; Y10T
428/31504 20150401; C09J 2301/122 20200801; C09J 7/29 20180101 |
Class at
Publication: |
428/332 ;
428/411.1; 428/702; 156/157 |
International
Class: |
B32B 9/04 20060101
B32B009/04; B32B 37/02 20060101 B32B037/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 3, 2008 |
DE |
10 2008 026 443.1 |
Jun 3, 2008 |
DE |
10 2008 026 447.4 |
Jun 3, 2008 |
DE |
10 2008 026 448.2 |
Nov 27, 2008 |
DE |
10 2008 059 381.8 |
Claims
1. Adhesive bonding system for joining flat webs when changing
rolls of such webs, comprising two adhesive tape boundary edges,
and further comprising a top carrier layer and a bottom carrier
layer a flat connecting element, having one or more boundary edges,
that connects the two carrier layers to one another to form a
connection, and is suitable for opening the connection under the
conditions of a static or flying roll change, two layers of
adhesive, each provided on a surface of each carrier layer that
faces away from the connecting element, where the connecting
element is not a layer of adhesive and the connection between the
connecting element and at least one of the carrier layers is not
brought about by means of further layers of adhesive, wherein at
least one of the boundary edges of the connecting element does not
extend in a straight line, and a straight-line emphasis line is
defined in relation to the at least one of the boundary edges, the
emphasis line of the at least one of the boundary edges extending
along a preferential direction, and the at least one of the
boundary edges having a multiplicity of regions lying on one side
of its emphasis line and also a multiplicity of regions lying on
the other side of its emphasis line.
2. Adhesive bonding system according to claim 1, wherein the
adhesive bonding system is in the form of an adhesive strip
extended in the preferential direction.
3. Adhesive bonding system according to claim 1, wherein the
connecting element is in the form of a multiplicity of individual
substantially two-dimensional elements.
4. Adhesive bonding system according to claim 1, wherein the
emphasis lines of at least two long edges run parallel and extend
in the preferential direction.
5. Adhesive bonding system according to claim 1, wherein the
emphasis line of the at least one of the boundary edges, not
extending in a straight line, of the connecting element to the
emphasis line of the boundary edge of at least one of the carrier
layers exhibits a spacing of 0.5 mm to 2.5 mm.
6. Adhesive bonding system according to claim 1, wherein the
emphasis line of the at least one of the boundary edges, not
extending in a straight line, of the connecting element to the
emphasis line of the boundary edge of at least one of the carrier
layers exhibits a spacing of 2.5 mm to 5 mm.
7. Adhesive bonding system according to claim 1, wherein the
emphasis line of the at least one of the boundary edges, not
extending in a straight line, of the connecting element to the
emphasis line of the boundary edge of at least one of the carrier
layers exhibits a spacing of 5 mm to 10 mm.
8. Adhesive bonding system according to claim 1, wherein the
emphasis line of the at least one of the boundary edges, not
extending in a straight line, of the connecting element to the
emphasis line of the boundary edge of at least one of the carrier
layers exhibits a spacing of 10 mm to 15 mm.
9. Adhesive bonding system according to claim 1, wherein the
connecting element comprises a polymer layer which is delaminable
either from the top carrier layer or from the bottom carrier
layer.
10. Adhesive bonding system according to claim 9, wherein a further
layer is provided between the polymer layer and the carrier layer
from which the polymer layer is delaminable.
11. Adhesive bonding system according to claim 1, wherein the
connecting element comprises a layer of a laminating composition,
the laminating composition forming a predetermined break point.
12. Adhesive bonding system according to claim 11, wherein the
laminating composition comprises easy-release additives, especially
calcium stearate, talc and/or polymers carrying stearyl groups.
13. Adhesive bonding system according to claim 11, wherein the
laminating composition comprises a binder, in particular a
polysaccharide compound, and also at least one surfactant.
14. Method of connecting two flat webs during flying roll change of
flat-web material wound up to form rolls, using an adhesive bonding
system according to any of claim 1.
15. Wound roll of an adhesive tape comprising an adhesive bonding
system according to any of claim 1.
Description
[0001] The invention relates to an adhesive tape for flying roll
change of flat-web material wound up to form rolls and a method of
flying roll change of flat-web material wound up to form rolls.
[0002] In the processing of flat-web material (paper, films,
nonwovens or the like) a roll change on the fly (flying splice) is
a common method of replacing an old, almost fully unwound roll by a
new roll without having to stop the quick-running machines in order
to do so. In the course of on-the-fly roll changes of this kind it
is common to employ (pressure-sensitive) adhesive tapes in order to
join (or splice) the end of the old web to the start of the new
web.
[0003] For years in this context there have been adhesive tapes
known which are adhered in a straight line beneath or atop the
uppermost ply of the new roll and so combine in one tape the
function of the roll closure and also of the adhesive splicing tape
(the adhesive tape that joins the new flat web (more particularly a
paper web) to the old, expiring flat web).
[0004] During the splicing operation it is necessary for the roll
closure to open in order to allow the new flat web to be attached
to the end portion of the expiring flat web, so that, after the
splicing operation, the new flat web runs off from the new roll in
a continuous operating regime.
[0005] U.S. Pat. No. 5,323,981 A discloses a two-sided adhesive
tape having on its outside a high-tack adhesive for flying splice.
On its reverse there are two adhesives positioned and
advantageously an adhesive-free zone between the adhesives. In this
arrangement, the rear adhesive, which is permanently adhesive, is
bonded to the uppermost ply of the new roll, and the front
adhesive, which is repositionable, is bonded via the uppermost ply
to the second ply. In this version, the repositionable adhesive
plays the part of the roll closure. In the case of flying splice,
the expiring web comes into contact with the new roll on the top
face of the adhesive tape. The repositionable adhesive detaches
from the material of the second ply, and the new roll is drawn into
the machine, held by the permanent adhesive at the end of the
adhesive tape.
[0006] WO 95/29115 A discloses a similar adhesive tape. This
two-sided adhesive tape has two adhesives on the top face and one
adhesive on the bottom face. This adhesive tape is fastened beneath
the uppermost ply of the new roll. In this arrangement, one
adhesive holds the uppermost ply. The second adhesive is
responsible for contact with the expiring web. On the reverse face
there is also a repositionable adhesive, which in the case of the
splice exposes the uppermost ply. Both adhesive tapes have a common
disadvantage. With both of them, the repositionable adhesive runs
openly through the finishing machine, with the consequence that
there may be instances of webs sticking to deflection rollers or
printing blankets. This may then lead to tears in the webs.
[0007] A remedy to this problem is taught by DE 196 28 317 A. The
adhesive tape has a construction similar to that of WO 95/29115 A,
but the repositionable adhesive on the reverse face is replaced by
a two-sided adhesive tape featuring a splittable carrier. In the
case of the splice, the carrier splits and, with the respective
remnants, covers the adhesives in such a way that they remain
non-adhesive. This prevents disruptive instances of sticking in the
course of passage through the finishing machines.
[0008] A further remedy is taught by DE 199 02 179 A. In that case
the splitting strip is recessed from the front edge. This recession
permits a significant increase in splicing efficiency. DE 198 41
609 A describes a double-sidedly adhesive attachment element. The
carrier is composed not of a single-ply paper but instead of a
paper/paper composite which is joined with curing adhesive dots.
This adhesive tape is also adhered beneath the uppermost ply. In
the case of the splice, the adhesive dots extract fibres from one
of the composite papers, thereby exposing the uppermost ply.
[0009] All of these products have a disadvantage. The splittable
system, whether it be a paper, a composite of two papers, a
paper/film composite, a composite of two films, or a polymer layer
which splits, exhibits a force peak at the moment of incipient
splitting, as a result of the fact that the splittable system
splits simultaneously over its entire width. Particularly when the
adhesive splicing tape is used on coated papers, and especially on
coated gravure papers, the force spikes lead continually to the
failure of the adhesive tape. One of the reasons for this failure
is that the splitting forces can be higher than the forces which
anchor the paper coating, in which case the coating separates from
the paper. Or else the splitting forces are in fact higher than the
internal strength of the paper, in which case there are paper
tears. In both cases the splice is unsuccessful.
[0010] An improvement is taught by DE 100 58 956 A. In order to
avoid a force spike, the splitting strip has a jagged design. The
tips of the jags point in the running direction of the operation,
and so, at the moment of splicing, the tip of the jag begins to
split. Because of the small area in the tip, the force values are
reduced as well. This system, however, has the disadvantage that,
at the tip of the jag, the bond area approaches zero. Accordingly
the bond strength at the tip is not enough to ensure splitting at
the tip. Depending on the quality of the paper to be split, there
is splitting beneath the tip, specifically at the point where the
bond strengths are higher than the splitting forces. In other
words, some unsplit components of the splitting strip pass through
the printing or paper further-processing machine, and may lead to
instances of contamination. Since the bond strengths of the
splittable system are dependent on the paper type, the size of
these unsplit components varies and so, too, does the force
required for splitting.
[0011] An improvement is taught by DE 10 2005 051 181 A. Here, the
splitting strip is not given a jagged design, but instead is
rounded at the tips. This leads to an increase in the bond area,
which always generates a sufficient bond strength and thereby
ensures reliable splitting. However, the non-linear geometries of
the splittable system exhibit a weakness. When the adhesive tape
featuring the splittable system is unwound from a roll of adhesive
tape, there are stresses at the leading edges of the splitting
system, which stand transversely to the direction of unwinding,
and, in certain cases, the splitting strip begins to split.
Premature splitting occurs in particular in the case of wave forms
or geometries which are distinguished by a high slope of the
geometry. Since the splitting system constitutes a coherent
two-dimensional structure, the unwanted splitting may run over a
relatively long section of the splittable system, and in certain
cases there may even be complete splitting of the wave-form
splitting strip. This is particularly critical in those cases in
which it is not noticed by the user, since the splice performance
falls. If the user notices the incipient splitting or complete
premature splitting of the splitting strip, the adhesive tape must
be newly applied, which is time-consuming and has an adverse effect
on productivity.
[0012] Moreover, this system is confined to those applications in
which the splittable system can be paper. For applications
particularly in the film-producing and -processing industry, paper
is an unwanted material of use. Here the system specified above
cannot be used. Furthermore, the splitting paper with its coating
of adhesive exhibits a restriction in the diversity of the
adhesives that can be used. In no case must the adhesives migrate
into the splitting paper because of inadequate viscosities, since
that can alter the splitting forces in an unwanted way and then
lead to faults in the application.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The invention will now be described in greater detail with
reference to the drawings, wherein
[0014] FIG. 1 is a cross-sectional view of an adhesive bonding
system in an embodiment of the present invention;
[0015] FIG. 2 is a cross-sectional view of an adhesive bonding
system in an embodiment of the present invention;
[0016] FIG. 3 is a cross-sectional view of an adhesive bonding
system in an embodiment of the present invention; and
[0017] FIG. 4 is a cross-sectional view of an adhesive bonding
system in an embodiment of the present invention;
[0018] The object is achieved by means of an adhesive bonding
system for joining flat webs when changing rolls of such webs,
comprising two adhesive tape boundary edges, which advantageously
run substantially parallel and in particular form the long edges of
an adhesive tape, further comprising at least one top carrier layer
and one bottom carrier layer, and also a flat connecting element
that connects the two carrier layers to one another and is suitable
for opening the connection under the conditions of a static or
flying roll change, and further comprising two layers of adhesive
which are each provided on the surface of each carrier layer that
faces away from the connecting element, the connecting element not
being a layer of adhesive, and the connection between the
connecting element and at least one of the carrier layers not being
brought about by means of further layers of adhesive. For the
adhesive bonding system of the invention it is the case that at
least one of the boundary edges of the connecting element does not
run in a straight line (in other words, is non-linear), and a
straight-line emphasis line (main direction line) is defined in
relation to this boundary edge, the emphasis line of this boundary
edge extending along a preferential direction, and this boundary
edge has a multiplicity of regions lying on one side of its
emphasis line and also a multiplicity of regions lying on the other
side of its emphasis line.
[0019] Preferably, the connecting element does not comprise layers
of adhesive; very preferably, the adhesive tape has no layers of
adhesive between the carrier layers. Non-adhesive in the sense of
this specification means that the layer in question is unable, in
application, to expose any adhesive or tacky surfaces when it is
destroyed or parted from its substrate. Accordingly, although the
layers may be applied, for example, as adhesive substances and may
in that state bring about the joining connection, there is
nevertheless drying in these cases subsequently, and so the layer
that remains would no longer be adhesive or tacky even if it were
to be exposed. In other words, the layer that is present in the
adhesive tape that remains for application is a layer which has
non-adhesive properties irrespective of it being lined by a carrier
material or by other substrates. Conversely, pressure-sensitive
adhesives remain tacky per se even when they have bonded two
substances to one another; their functionality (their adhesive
bonding effect) to the outside is hindered only by lining. For the
purposes of this specification, therefore, layers of composition
are not adhesives especially when in the application state, i.e.,
in particular, in the dried state, they possess no self-adhesive
properties, in other words have no tack.
[0020] When the view is directed onto the individual layers (e.g.
carrier layers, layers of adhesive or the layer that forms the
connecting element), the course of the respective boundary edges of
the layers can be interpreted mathematically as curves. The line
referred to as the emphasis line (also referred to as the main
direction line) of an edge is, for the purposes of this
specification, the line which divides the curve that describes the
respective edge in such a way that the total area of the areas that
lie on one side of the emphasis line, these areas being enclosed by
the straight line representing the emphasis line and by the curve
itself, and the total area of the areas that lie on the other side
of the emphasis line, these areas being enclosed by the straight
line that forms the emphasis line and by the curve, are
identical.
[0021] In an outstanding approach the emphasis lines [main
direction lines] of the at least two adhesive tape boundary edges
(long edges of the adhesive tape) run parallel and extend into the
preferential direction, in other words into the direction in which
the emphasis line of the non-linear edge of the connecting element
also extends.
[0022] The connecting element may be arranged flush to one of the
long edges of at least one carrier layer, especially in such a way
that the points projecting furthest forward of the edge, not formed
in a straight line, of the connecting element are situated on the
corresponding carrier layer edge. For the use of the invention in
flying roll change, however, it has emerged as being very
advantageous if the connecting element is arranged with a spacing
from a long edge of at least one carrier layer, advantageously of
both carrier layers, the spacing being defined as the distance of
the line through the points, situated furthest in the direction of
the corresponding carrier layer edge, of the connecting element
boundary edge to the edge or edges of the carrier layer or layers,
or, in the case where the carrier layer edge or edges is or are
non-linear, to their emphasis line or lines.
[0023] This new adhesive bonding system solves the three problems
described above. The innovative adhesive tape construction prevents
the splitting strip starting to split on unwind. The plane of force
on unwinding from the roll is located between the adhesive of the
open side and the parting medium; the connecting medium is lined by
a carrier and is therefore not exposed to stress, and so there is
no premature parting in the connecting plane.
[0024] Since the carrier materials need not necessarily be produced
from a paper, it is possible to provide a paper-free product. Since
both adhesives are coated on a carrier, which can be stable to
migration, it is possible to coat adhesives of any viscosity onto
both sides.
[0025] Very advantageous is an embodiment in which the emphasis
line of the at least one boundary edge, not extending in a straight
line, of the connecting element to the emphasis line of the
boundary edge of at least one of the carrier layers exhibits a
spacing. The spacings are dependent, in addition to application
speed, on the splitting energy (across the width of the connecting
element) and on the maximum force during the splitting process. The
maximum force and the splitting energy are measured by a splitting
in the application direction (T-block), in other words, in
particular, perpendicular to the main direction line (which in a
preferred version corresponds to the longitudinal direction of the
adhesive tape).
[0026] Both criteria here are important for the respective
application.
[0027] The maximum value of the splitting force can be adjusted
through the nature of the polymer (layer forming connecting
element) or the coat weight of the polymer. The splitting energy
then comes about additionally through the width of the connecting
element to be split, and the design of the boundary edge. Splitting
force values, and also the maximum value of the splitting force,
are measured in the application direction, in other words
perpendicular to the main direction line of the non-linear side of
the connecting element (in other words, in particular,
perpendicular to the longitudinal direction of the adhesive tape).
In this procedure, the top carrier is peeled at a 90.degree. angle,
in a tensile testing machine, from the bottom carrier, and the
connecting element parts ("splits"). The peel speed is 300 mm/min.
The initial value of the splitting force (i.e. the splitting force
value when the connecting element starts to split) is recorded, as
are the split propagation forces, which can be determined across
the width of the connecting element during splitting. The splitting
energy can be determined with the known width of the parting system
(connecting element).
[0028] Splitting forces (split propagation force after splitting
process has commenced) can likewise be measured in the direction of
the main direction line of the connecting element, in other words
in particular in the longitudinal direction of the adhesive tape.
The values specified in this direction are determined by a
measurement in which the top carrier is peeled at a 180.degree.
angle, in a tensile testing machine, from the bottom carrier, with
the connecting element parting ("splitting"); the peel rate here as
well is 300 mm/min.
[0029] In the absence of further remarks when reporting splitting
force values and splitting energy values in the context of this
specification, the figures relate in each case to the measurement
in application direction.
[0030] For thin, tear-sensitive materials, the maximum value of the
splitting force ought advantageously not to exceed 1 N/cm, and the
splitting energy ought to be less than 80 Nmm. In the case of
thicker materials that are less sensitive to tearing, the values
can be higher.
[0031] With regard to the spacing, it is the case that, the faster
the splicing operation takes place in the application, the smaller
the spacing from the leading edge ought to be, despite the fact
that a greater spacing would facilitate splitting and hence would
increase the splicing efficiency. Conversely to this is the effect
that, at high speeds, there is an increase in the risk of the
leading edge turning over.
[0032] The stated spacing between the emphasis line of the boundary
edge, which does not extend in a straight line, of the connecting
element and the emphasis line of the boundary edge of at least one
of the carrier layers is with particular advantage up to 15 mm and
ought preferably to be at least 0.3 mm.
[0033] For applications, in particular, in a speed range from
approximately 33 m/s to approximately 15 m/s, a spacing of 0.3 mm
(advantageously 0.5 mm) to 2.5 mm is ideal. Particularly for speeds
of approximately 15 m/s to approximately 9 m/s, the spacing ought
preferably to be 2.5 mm to 5 mm. The selected spacing can be larger
because, owing to the lower speeds, there is not such a high risk
of the leading edge turning over. In particular for speeds of
approximately 9 m/s to approximately 5 m/s, the spacing ought
advantageously to be 5 mm to 10 mm, and, in particular, in the case
of almost static applications, the spacing ought preferably to be
between 10 mm to 15 mm (limits included).
[0034] The spacings are independent of the width of the adhesive
tape.
[0035] FIGS. 1-4 show--schematically and without wishing
unnecessarily to restrict the inventive concept by the embodiments
depicted--four different embodiments of the adhesive bonding system
of the invention in a side section, with adhesive tapes of the
invention resulting in particular from quasi-infinite extension of
the adhesive bonding systems perpendicularly into the plane of the
paper.
[0036] FIG. 1 shows an inventive adhesive bonding system K having a
flat connecting element 1 between two carrier layers 2, 2' (a top
carrier layer 2 and a bottom carrier layer 2'), which in turn are
each coated with an adhesive 3, 3', in particular with
pressure-sensitive adhesives (layers of adhesive 3, 3', each
provided on the surface of each carrier layer 2, 2' that faces away
from the connecting element 1). Optionally, there may be a liner 4
on at least one of the layers of adhesive 3, 3', particularly the
layer of adhesive 3 on the top carrier layer 2 (depicted thus by
way of example in the figures), which advantageously is divided
into two sections 4a, 4b by a cut 5, a perforation or the like.
[0037] The adhesive bonding system has the outer adhesive tape
boundary edges Ka and Kb.
[0038] At least one of the boundary edges of the connecting element
1a, 1b does not extend in a straight line (in this case the edge
1a), depicted in FIG. 1 by the points 1c lying furthest in the
direction of the adhesive bonding system edge Ka, and by the points
1d of the connecting element edge that lie furthest back. This
connecting element edge 1a may, for example, extend in the form of
a wave, and so in this case, in FIG. 1, the positional numeral 1c
would represent the "crests" and the positional numeral 1d the
"valleys" of the waves.
[0039] FIG. 2 shows an embodiment of the invention in which the
boundary edge 1a of the connecting element 1 is advantageously
recessed by the distance A (with regard to the distance A, see also
the remarks above).
[0040] FIG. 3 depicts, on the basis of an exemplary embodiment, the
possibility that the opposite boundary edge 1b of the connecting
element 1 may likewise be arranged with recession from the
corresponding adhesive tape edge Kb, and so the connecting element
1, as viewed from the boundary edge 1a, extends only over a limited
portion of the adhesive tape K.
[0041] FIG. 4 shows by way of example, using a further embodiment,
that the second carrier 2' (the bottom carrier in the figure) may
be of narrower design, corresponding possibly, for example,
substantially to the width of the connecting element 1. In this
case the bottom carrier 2' may also be made wider than the
connecting element 1 but narrower than the top carrier 2 (not
depicted in the figure).
[0042] Since successful splicing is dependent on the total energy
of the splitting process, the invention affords the advantage that
different widths of the connecting element can be levelled by the
wave form. In other words, with different widths of the adhesive
tape, equal total energy values can be set through the wave
geometry without having to adapt the polymer used or its coat
weight.
[0043] The non-straight-line boundary edge may be designed in
particular in the form of a wave line, which may be of uniform or
non-uniform design. This wave form may be either symmetrical or
asymmetrical. A symmetrical wave form comes about in particular
from the boundary edge having periodically repeating sections for
each of which it is possible to define a mirror axis which is
arranged, in particular, perpendicularly to the emphasis line of
the corresponding edge.
[0044] The edges of the connecting element may advantageously be
shaped in a manner like that depicted for the edges of a readily
splitting adhesive tape in DE 10 2005 051 181 A. Accordingly, for
this inventive embodiment, the at least one non-straight-line
boundary edge of the connecting element is designed in such a way
that it has projections which at their furthest-projecting points
are rounded.
[0045] In a development of this embodiment, the non-straight-line
edge at its furthest-recessed points is likewise of rounded design,
preferably such that at these points the curvature is substantially
sharper than at the projecting points. Advantageously, in each case
between a furthest-projecting point and its closest
furthest-recessed point, the non-straight-line edge is continuously
differentiable, preferably with three inflection points. In another
advantageous embodiment, in each case between a furthest-projecting
point and its closest furthest-recessed point, the
non-straight-line edge is continuously differentiable, with one
inflection point. In a subsequent, inventively advantageous
development, the non-straight-line edge is composed of an
alternating sequence of semi-circles.
[0046] In one advantageous embodiment of the adhesive bonding
system of the invention, for the at least one non-straight-line
boundary edge of the connecting element, the negative of each
recess is of narrower design than the positive of an adjacent
projection. It may also be advantageous for the teaching according
to the invention that the at least one non-straight-line boundary
edge of the connecting element has two or more families of
projections which project to different extents in accordance with a
regular pattern.
[0047] In one advantageous embodiment of the splittable adhesive
bonding system of the invention, both boundary edges of the
connecting element do not extend in a straight line, and in
particular possess the same period length.
[0048] In one advantageous development of the invention, it is the
case, for the connecting element of the adhesive bonding system,
that its leading edge and its trailing edge extend parallel to one
another, so that, in spite of the non-linearity of the two
connecting element edges, the width of the connecting element is
the same everywhere. Reference is made to the corresponding
geometries as depicted in DE 10 2005 051 181 A, the explanations
therein concerning the edge profiles, and the figures therein, and
so these are considered to be included in the disclosure content of
the present specification.
[0049] Advantageous developments of the invention in relation to
the profile of the at least one non-straight-line boundary edge of
the connecting element are distinguished by the fact that this edge
is not symmetrical with respect to a mirror axis--in particular to
a mirror axis which stands perpendicularly to the emphasis line of
said edge.
[0050] This can be brought about advantageously by it being the
case that--in a preferential direction along the emphasis line--for
the majority of the projections the rising curve region up to the
furthest-projecting point of the projection is less steep than the
falling curve profile subsequent to this point of furthest
projection; that the curve describing the boundary edge thus runs
flatter in the rising region up to the projection maximum, for a
multiplicity of the projections, than in the subsequent falling
region. The steepness of each curve section also referred to as
curve region) here is regarded as being the amount of the slope of
a straight line which passes through two points bounding the
respective curve section. The steepness therefore corresponds
mathematically to the average of the first derivative of the curve
section, insofar as the curve section can be represented as a
Riemann integral of its first derivative.
[0051] An "askew" wave form of this kind may be realized in
particular as an onward development of the embodiment corresponding
to the edge forms of the kind known for adhesive tape edges from DE
10 2005 051 181 A.
[0052] Advantageous embodiments of the connecting element are such
that its second boundary edge, which is opposite to the
non-straight-line boundary edge, is designed in the form of a curve
which is produced by parallel displacement of the curve describing
the first boundary edge along a line standing perpendicular to its
emphasis line--and, if appropriate, a simultaneous displacement
along the emphasis line.
[0053] Another realization of the teaching according to the
invention is produced by adhesive tapes in which the connecting
element is constructed in the form of a multiply interrupted strip
which extends in the longitudinal direction of the connecting
element. In this arrangement each segment has one or more
projections, particularly those which are of rounded form at their
furthest-projecting points.
[0054] The adhesive bonding system of the invention differs from
those of the prior art in particular by the fact that the
connecting element between the two carrier layers is non-adhesive
and is non-adhesively joined at least to one of the carrier layers.
With particular advantage the adhesive bonding system of the
invention has a connecting element which is not realized by a
two-dimensionally splitting paper.
[0055] In the case of a connecting element which comprises, for
example, a splitting paper provided adhesively at one or between
two carrier layers, the forces must be set as inherent properties
of the paper. It is correspondingly difficult to find suitable
papers for this end use. If a connecting element is provided as
proposed in the present specification, the advantage is gained
that, through the choice of suitable polymers, laminating
compositions or the like, and through the specific shaping of the
element, influence may be had, very conveniently, over the
resulting splitting forces, and these forces can be set optimally
for the envisaged end use. Moreover, a connecting element of this
kind can be made very thin: whereas the prior art here provides at
least two layers of adhesive and a splittable ply, it is sufficient
in accordance with the invention for there to be at least one, thin
layer of a polymer, of a laminating composition or the like.
[0056] The connecting element is designed in particular in such a
way that, under the kind of stresses that occur in the course of
flying roll change, it reliably parts the join between the two
carrier layers. In this sense the connecting element represents a
"predetermined breakpoint" under such stress. For this purpose, the
adhesive bonding system, comprising the carrier layers and the
connecting element, is optimized in particular such that it
effectively transmits those forces which are directed, within the
plane of the adhesive bonding system, substantially transverse to
its longitudinal extent, whereas, with respect to forces in the
thickness direction of the adhesive bonding system, precisely on
the contrary, failure is actually desired under levels of force
which are as low as possible. Ensuring this behaviour is critically
influenced by the choice and the design of the connecting
element.
[0057] The connecting element may part from the top carrier layer
or from the bottom carrier layer in order to separate the join;
also realizable are embodiments where parting from both carrier
layers is possible. In the case of the last-depicted variant,
parting may take place simultaneously from both carrier layers, or
parting takes place, statistically, in some cases from one and in
some cases from the other carrier layer, without particular
preference. Embodiments are realizable, additionally, in which
parting is possible in principle from both carrier layers, but
parting from one of the layers is preferred.
[0058] One version of the connecting element has at least two
layers, the parting of the system occurring not by delamination
from one of the two carrier layers but instead by parting of the
two layers from one another. In order to improve the delamination
behaviour of one of the carrier layers or else--on the side which
is not to delaminate during the splicing operation--to impair such
delamination behaviour, it is possible, between the polymer layer
and the corresponding carrier layer, for a further layer to be
provided which produces or promotes the corresponding effect.
Advantageously it is possible for one of the carrier layers to be
pretreated or coated in such a way that delamination of the polymer
layer is promoted, and for the other of the carrier layers to be
pretreated or coated in such a way that the adhesion of the polymer
layer to that carrier layer is enhanced
[0059] It is very advantageous to provide only very thin layers or
to impregnate the carrier layer or layers themselves accordingly,
in order to leave the overall thickness of the adhesive bonding
system as low as possible. Moreover, the connecting element may be
designed in such a way that the parting process of the two carrier
layers from one another is brought about by rupturing of the
connecting element--or of one layer of the connecting element--and
that, in other words, there is no two-dimensional splitting in
respect of this layer. In this case, residues of the ruptured layer
of the connecting element remain both on the top carrier layer and
on the bottom carrier layer.
[0060] In one advantageous embodiment of the adhesive bonding
system of the invention, the connecting element does not represent
a continuous layer. In particular the connecting element may be
composed of a multiplicity of individual area elements which are
provided between the carrier layers. Arrangements of this kind can
be produced advantageously, for example, by applying the connecting
element by screen printing or by means of a patterned roller to one
of the carrier layers. The individual area elements may be arranged
in particular in such a way that they are arranged contactlessly
with respect to one another. Via the geometry of the area elements,
i.e., for instance, via their geometric form, their size and/or
their arrangement relative to one another, it is possible with
outstanding effect to set the release forces needed to separate the
two carrier layers from one another.
[0061] A feature of the connecting element between the two carrier
layers is that it is connected non-adhesively to at least one of
the two carrier layers, and with particular advantage to both
carrier layers. By foregoing the use of layers of adhesive, the
adhesive bonding system can be made very thin, which is
advantageous for its use in particular in flying roll change. Hence
the paper web is run, for example, in printing and paper-finishing
machines at high speeds through very narrow areas, such as roller
pairs, nips, calendar stats, and the like; in the printing industry
they are finally also introduced, for example, into folding
apparatus. The thinner the adhesive tape can be made--with
sufficient quality for the requirements associated with the
splice--the lower the risk of unintended tearing or other faults in
the automatic operation. Each of these faults is associated with
considerable costs, since the plant must be halted and started up
again later. Through the adhesive tape according to the invention,
success has been achieved in largely avoiding these faults.
[0062] The connecting element is capable, under the conditions of a
static or "flying" (in particular, automated) roll change, of
opening the connection, and hence takes on the function of a
"predetermined breakpoint". As a result of the absence of layers of
adhesive, it is usually possible, for the purpose of producing the
splitting process, not to use splittable paper, as is known from
the prior art.
[0063] In one advantageous procedure it is possible to use a
connecting element that comprises a polymer layer which is
delaminable either from the top carrier layer or from the bottom
carrier layer. Also realizable are embodiments in which the polymer
layer is delaminable from both the top and the bottom carrier
layers--for instance when in terms of apparatus there are no
difficulties associated with where the delamination takes place. In
the simplest version of this embodiment the polymer layer
constitutes the connecting element.
[0064] The polymer layer or layers of the connecting element can be
produced, for example, by applying the polymer that produces the
polymer layer (a varnish, for instance) to one of the carrier
layers--or, if appropriate, to an interlayer (more particularly a
functional interlayer)--by printing, for example. If it is desired
not to apply the polymer layer over the full area, it is
outstandingly possible, for example, to employ screen printing.
Placed atop the as yet undried polymer solution or the as yet
uncured polymer can then be a further layer or, in particular--for
connecting elements which are constructed from a polymer layer--the
second carrier layer, so that drying and/or curing produces an
assembly of the carrier layers by means of the polymer. Through the
choice of the chemical nature of the polymer, the amount of polymer
applied, the form of the application (full area, partial area,
local, etc.), the choice of the carrier layer materials and the
nature of the pretreatment of the carrier materials, it is possible
to influence the force which is needed in order to delaminate the
assembly, and also, furthermore, to influence the matter of from
which of the carrier layers the polymer layer preferentially
delaminates.
[0065] As a polymer layer for the adhesive bonding system of the
invention it is possible with great advantage to use those polymers
of the kind disclosed in WO 99/46196 A, particularly at page 9
lines 15 to 29 therein. Hence the polymer for the polymer layer may
in particular be selected advantageously from the group
encompassing polyvinyl chlorides, polyvinylidene chloride,
polyvinyl alcohols, polyvinyl acetates, polyvinylpyrrolidones,
copolymers of vinyl chloride and vinyl acetate. As additives it is
possible for example to use wetting agents, defoamers, plasticizers
and/or fungicides. One preferred polymer which is disclosed in the
aforementioned publication and can also be used outstandingly in
the present invention is a repulpable polymer, based, for example,
on polyvinyl alcohol, which preferably further comprises one or
more plasticizers. Plasticizers used with particular preference are
compounds such as polyols (diethylene glycol, for example),
hydroxy-modified rubbers or a combination of both.
[0066] Having emerged as being a further system useful to
outstanding effect in accordance with the invention for polymer
layers for the connecting element are primers of the kind known
from the building and DIY sector for the preparation of paint
finishes, renders, adhesives and floor-levelling compositions,
where they are used in particular for the pretreatment of highly
absorbent substances such as plaster building materials or
chipboard, for example. Reference may be made here in particular to
the polyacrylate-based primers. One commercially available
deep-down primer which has emerged as being particularly suitable
for use for the polymer layer or layers of the connecting element
is sold under the name "Beste Basis" by the company Lugato,
Hamburg, Germany.
[0067] In a further advantageous embodiment it is possible as the
connecting element to make use in particular of systems which can
be obtained by drying water-based compositions (water-based
laminating composition). In the simplest version of this
embodiment, the layer of laminating composition constitutes the
connecting element. In this case the laminating composition is
selected such that the assembly meets the requirements during the
splicing operation, in other words produces the desired
predetermined breakpoint. The laminating compositions are
preferably selected such that, in the form of their dried films,
even at relatively high temperatures, they possess no adhesive
force, so that the areas that are exposed after the assembly has
parted do not contaminate mechanical parts or production material.
For use in the paper and printing industries it is desirable that
the recycling process is not disrupted. Accordingly it is
advantageous to select water-based compositions of the laminating
composition, in which the auxiliaries customary in papermaking may
be present.
[0068] As water-based compositions it is possible with great
advantage to use cellulose-based systems, particularly those based
on methylcellulose. Systems of this kind are available commercially
as wallpaper pastes.
[0069] Particularly advantageous laminating compositions which can
be used to outstanding effect for the adhesive bonding system of
the invention are disclosed in, for example, EP 1 076 026 A.
Laminating compositions of this kind which can be employed
advantageously comprise, in addition to a binder, silicone-free
additives with an easy-release activity; where necessary,
elasticizing additives may additionally be present. As binders it
is possible with advantage to use modified starches, or binders of
the kind that have long been in use for wet adhesive tapes. As
release agents the laminating composition preferably comprises
easy-release additives, especially stearyl derivatives, in
particular calcium stearate, talc and/or polymers which carry
stearyl groups. Advantageously it is possible as release agents to
use dispersions of polymeric release agents, such as dispersions
based on copolymers of stearyl methacrylate or stearyl derivatives
of maleic acid with styrene, for example. As elasticizing agents it
is possible for example for water-soluble polyglycols to be used.
In particular, aqueous preparations with 10% to 90% by weight of
binder and 10% to 90% by weight of release agent and also up to 60%
by weight of elasticizing agent can be used as a laminating
composition. As binders it is preferred to use starch derivatives,
e.g. anionic potato starch, in fractions of 30% to 70% by weight.
Release agents used are preferably talc, Ca stearate and/or
release-active copolymers with stearyl groups, in fractions of 30%
to 80% by weight. For elasticization, polypropylene glycols or
polyethylene glycols have proved to be highly suitable, preferably
in amounts between 0% to 15% by weight. In this context the
products of higher molecular mass that are solid at room
temperature are used primarily. Further elasticizing agents which
can be used to good effect in relatively large proportions are gum
arabic and plastics having a similar profile of properties. The
layer thickness of the laminating composition after drying is
situated preferably in the range from 5 to 20 g/m.sup.2. Likewise
very effective for use as the connecting element of the adhesive
bonding system of the invention can be laminating compositions of
the kind described in the as yet still unpublished DE 10 2008 023
020, filed recently by the applicant.
[0070] The laminating adhesive that is described therein and can
likewise be used with outstanding effect for the inventive adhesive
bonding system of the present specification comprises at least one
binder, more particularly a polysaccharide component, and at least
one surfactant component, which acts in particular as a release
agent. The surfactant component may be a single surfactant or may
comprise two or more surfactants. The laminating adhesive can where
necessary advantageously comprise further components, including, in
particular, elasticizing additives (also elasticizing agents
below). In one very preferred procedure the polysaccharide
component is starch, gum arabic or derivatives of the
aforementioned compounds.
[0071] The binder component may, furthermore, also be, for example,
a stearate, more particularly magnesium stearate and calcium
stearate. The composition of the binder component may also be such
that a mixture of starch with one or more further binders is used.
Starch as a binder has the clear advantage that the
screen-printability possessed by the laminating composition is very
good.
[0072] Laminating compositions that are particularly preferred in
accordance with the invention have a polysaccharide fraction of up
to 98% by weight, more preferably of up to 85% to 95% by weight,
even better from 90% to 95% by weight. With particular preference
it is possibles to use starch derivatives, especially hydroxypropyl
ethers based on potato starch. One such starch is available, for
example, from the company Emslandstarke under the name Emsol
K55.
[0073] The surfactant content is very preferably 2% to 20%, better
5% to 15%, ideally 5% to 10% by weight. The above fraction figures
refer, both for the polysaccharide component and for the surfactant
component, to the mixture of surfactant and polysaccharide, in each
case in the form of the amount based on the solids fraction.
Additionally present for the preparation of the laminating
composition is a solvent, more particularly water, preferably in
fractions of 50% to 80% by weight. To prepare the laminating
adhesives it is possible in particular to proceed by adding the
solid surfactant to a 20% to 40% strength aqueous solution of the
polysaccharide component.
[0074] Further additives to the laminating composition that may be
used are, for example, talc, calcium stearate and/or release-active
copolymers with stearyl groups, in fractions of 30%-80% by weight.
Talc may be used in particular as a filler in order to adjust the
screen-printability.
[0075] For elasticization, polypropylene glycols or polyethylene
glycols have proved to be highly suitable, preferably in amounts
between 0% to 15% by weight. In this context the products of
relatively high molecular mass that are solid at room temperature
are used primarily. Further elasticizing agents, which can be used
effectively in relatively large proportions, are gum arabic and
plastics having a similar profile of properties.
[0076] Surfactants are used as release agents. Particular
preference is given to selecting nonionic and/or anionic
emulsifiers. These surfactants may be monomeric, oligomeric or else
polymeric in nature. Use is made preferably of surfactants with
long side chains, in particular with side chains having 8 to 18 C
atoms. Polar surfactants with relatively long-chain alkyl radicals
have emerged as being particularly preferred, especially those
surfactants with alkyl chains having at least 8, better still
having at least 12, C atoms.
[0077] The following compounds have emerged as being particularly
advantageous release agents for the present invention: sodium
octadecylsulfosuccinate, sodium dialkylsulfosuccinate, Na n-dodecyl
sulphate, sodium lauryl sulphate, ammonium lauryl sulphate, sodium
oleylcetyl alcohol sulphate, fatty alcohol polyglycol ethers, fatty
alcohol ethoxylate, nonylphenol ethoxylate. Disodium
n-octadecylsulfosuccinate (ODSS) has emerged as being a
particularly outstanding release agent in the inventive sense. When
a laminating composition on this basis was used, it was possible to
produce adhesive tapes that could be used with particular success
(faultlessly) for a flying roll change. The compounds which can be
used to outstanding effect as release agents for preparing the
laminating composition of the invention include Na
octadecylsulfosuccinate, Na dialkylsulfosuccinate, Na
n-dodecylsulphate, NH.sub.4 lauryl sulphate, Na oleylcetyl alcohol
sulphate, fatty alcohol polyglycol ethers, fatty alcohol
ethoxylate, nonylphenol ethoxylate.
[0078] In one advantageous procedure the adhesive bonding system of
the invention is lined on at least one of its layers of adhesive,
at least temporarily, with a release material, in particular for
the purpose of facilitating handling. For this purpose it is
possible to use the materials that are customary to the skilled
person for this end use; the liner is composed more particularly of
a siliconized material, preferably of siliconized paper. The liner
may be divided, or prepared for possible division, into two
sections with a cut or predetermined breakpoint, more particularly
in the form of a perforation, kiss cut, slitting or the like, that
runs in the longitudinal direction of the adhesive tape. The
adhesive bonding system of the invention may in particular be
present in the form of an adhesive strip that is extended in the
preferential direction (and is also referred to below as an
adhesive tape). The adhesive bonding system in adhesive tape form
can be presented to outstanding effect in a form in which it has
been wound up to form a roll (more correctly, from a geometric
standpoint, an archimedean spiral).
[0079] The invention further provides a method of flying roll
change using an adhesive bonding system of the invention.
[0080] The method of the invention of connecting two flat webs
during flying roll change of flat-web material wound up to form
rolls is described below with reference to an exemplary embodiment,
without wishing the subject matter of the invention to be
restricted unnecessarily through the choice of the exemplary
embodiments. In a first variant of the method of the invention, the
topmost flat web turn (in particular its end or its end region) of
a new roll, having an adhesive bonding system of the invention that
is suitable for obtaining an adhesive bond which can be released
again in such a way as to be free from adhesive areas, is fixed to
the underlying flat web turn, so that a part of a self-adhesive
that is needed for joining to the outgoing flat web is exposed.
Thereafter the new roll thus equipped is placed adjacent to an
almost entirely unwound, old roll that requires replacement, and is
accelerated to substantially the same rotary speed as that roll,
and then is pressed against the old flat web, the exposed
self-adhesive of the adhesive bonding system bonding to the old
flat web when the webs have substantially the same speeds, while at
the same time the bond of the topmost flat web ply (end ply of the
turn) to the underlying flat web ply parts two-dimensionally in
such a way that, after the parting operation, there are no adhesive
regions exposed. The parting of the bond of the topmost flat web
ply to the underlying flat web ply is accomplished in this case, in
particular, by one of the parting mechanisms already described for
the adhesive bonding system of the invention--in other words, by a
parting of the connecting element, as described in detail
above.
[0081] An adhesive bonding system of the invention is used, in
other words a system comprising a top carrier layer and a bottom
carrier layer, a flat connecting element that connects the two
carrier layers to one another and is suitable for opening the
connection under the conditions of a static or flying roll change,
and also two layers of adhesive which are each provided on the
surface of each carrier layer that faces away from the connecting
element, the connecting element not being a layer of adhesive, and
the connection between the connecting element and at least one of
the carrier layers not being brought about by means of further
layers of adhesive, and, furthermore, at least one of the boundary
edges of the connecting element does not run in a straight line,
and a straight-line emphasis line (main direction line) is defined
in relation to this boundary edge, the emphasis line of this
boundary edge extending along a preferential direction, and this
boundary edge having a multiplicity of regions lying on one side of
its emphasis line and also a multiplicity of regions lying on the
other side of its emphasis line.
[0082] In one advantageous development of the inventive method the
adhesive tape is bonded at right angles to the running flat web. In
other advantageous versions of the method according to the
invention, the adhesive tape can also be bonded at an acute angle
of up to 300 with respect to the running flat web, more
particularly of up to 10.degree.. In that case, particularly in the
case of the adhesive tape bonded at right angles to the running
flat web, the parting process preferably takes place transversely
to the emphasis line of the non-straight-line boundary edge of the
connecting element: that is, the parting process begins in those
projections of the connecting element that project out the
furthest.
[0083] The flat webs are, in particular, paper webs and/or film
webs and/or textile material webs (wovens, knits, nonwovens or the
like).
[0084] Through the form of the connecting element it is possible
advantageously to set the corresponding parting force or release
force, as a function of the material. The form or geometry of the
connecting element means that as small as possible a force is
needed for incipient splitting in the transverse direction of the
adhesive tape. However, this force must also not be too small, in
order not to cause premature opening of the roll of flat-web
material to be spliced that is bonded with the adhesive tape of the
invention, in the acceleration phase of the splicing operation, and
so cause tearing. This applies in particular to belt-driven lines
in which a particular strength is necessary in the region of the
belt.
[0085] The adhesive tape of the invention has shown itself to be
outstandingly suitable for the intended utility.
* * * * *